The present embodiments relate to a radioscopy device, which includes a detector grid and a scattered radiation matrix.
In radiological imaging, stringent demands are made in terms of image quality. In radiological images, for example, in medical radiological diagnosis, an object to be examined has X-radiation from an approximately point-shaped X-ray source passed through it. The distribution of the attenuation of the X-radiation on the side of the object diametrically opposite the X-ray source is detected two-dimensionally with a detector.
The radiation originating at the X-ray source includes primary rays and scattered rays. The primary rays strike the detector rectilinearly. Scattered rays are scattered in the object because of unavoidable interactions. The scattered rays may also strike the detector. The scattered rays, which as a function of properties of the object, can make up over 90% of the total signal striking the detector in the case of diagnostic images. The scattered rays represent an unwanted noise source, which makes the detectability of fine differences in contrast considerably more difficult.
To reduce the scattered rays striking the detector, a scattered radiation matrix is placed between the object and the detector. The scattered radiation matrix includes regular absorbing structures that absorb the X-radiation, and between the absorbing structures, through conduits are embodied for the passage of primary rays with little or no attenuation. Scattered radiation matrixes generally comprise alternating, very thin strips of lead, paper, plastic or aluminum. However, the absorbing structures cause image interference. Image interference is reduced using the thinnest and most uniform possible embodiment of the absorbing structures.
In X-ray radioscopy, the conventional film/foil systems are increasingly being replaced by electronic imaging systems, which are essentially digital imaging systems. Electronic imaging systems scan the analog image signal, for example, by using CCD image amplifiers or a flat detector. The analog image signal may be reprocessed and stored in memory. Such scanning systems include individual identical receptor elements, which are the CCD or semiconductor detector elements, disposed in a uniform grid. Because of the production technology, these elements are generally not square and do not completely fill the area available for a single element with a receptive area, for example, the fill factor is less than 100%.
When digital detectors are used in conjunction with regular, immobile scattered radiation matrixes, the structures of the pixels can interfere with those of the scattered radiation matrixes. If very fine scattered radiation matrixes are used, for example, whose number of lines is in the range of the scanning frequency of the detectors, then in addition to the direct image interference of the absorbing structures, moiré artifacts are created. Moiré artifacts are additional image interferences that are an impairment to the medical evaluation.
To minimize moiré artifacts, German Patent Disclosure DE 103 05 106 A1 arranges absorbing structures of the scattered radiation matrix in the form of random, aperiodic patterns. However, the production of such structures is complicated and expensive.